GIS in Public Health or As the World Turns

1
GIS in Public Health-- or --As the World Turns

• Lois M. Haggard, Ph.D.
• March 17, 2003
• CFHS Program Managers Meeting

2
Outline

• Brief review of GIS constructs
• Spatial analysis and public health examples
• How to - local resources for mapping your data

3
Disclaimer

• I am not a GIS specialist
• I learned much of what I know in preparation for
  this presentation!
• I am glad to share what I have learned, and we
  can go forward together.

4
Basic Theory and Constructs

• GIS Defined
• A Geographic Information System consists of all
  the computer hardware, software, personnel and
  data that are required to map and analyze spatial
  data.
• A popular GIS software provider is ESRI
  (Environmental Systems Research Institute). They
  produce ArcView (desktop version), ArcIMS (for
  Internet applications), and ArcExplorer
  (freeware), among others.

5
Basic Theory and Constructs

• GIS versus GPS
• GIS is not GPS - but GPS is used by GIS
• GPS stands for Global Positioning System, which
  is a system of satellites circling the Earth, and
  the devices that interpret the data from those
  satellites, providing coordinates on the Earths
  surface. (GPS Geocodes your position on the
  Earths surface.)

6
Basic Theory and Constructs

• Purpose of GIS in Public Health
• Descriptive epidemiology -
• Person
• Place
• Time
• Maps used in public health generally depict how
  events that happened to persons during a
  particular time window are distributed over
  geographic space.
• CDC URL for GIS in public health --
  http//www.cdc.gov/nchs/gis.htm

7
Basic Theory and Constructs

• Purpose of GIS in Public Health
• Disease and injury events have spatial
  associations we may want to be aware of.
• Infectious diseases spread from person to person
• Environmental exposures (e.g., cancer downwind
  from nuclear testing)
• Heath care utilization is related to proximity to
  facilities
• Lifestyle factors can be related to environment
• Health status is related to other social factors
  (e.g., income, education) that are spatially
  related.

8
The Global Perspective

• -NEWS FLASH-
• Earth Not Flat!
• -- But maps ARE --
• A location on the Earth is communicated in
  latitude and longitude.
• A location on a map is communicated using
  Cartesian coordinates (x, y, sometimes z)

9
Cartesian Coordinates
10
Projections and Distortion

• Map projections project the Earth's surface onto
  a flat plane.
• There are numerous types of projection, each of
  which distorts some parameter of the Earth's
  surface be it distance, area, shape, or
  direction.
• Projection decisions always represent tradeoffs
  between different types of distortion and
  convenience.

11
Mercator Projection
12
Mercator Projection
13
(No Transcript)
14
Transverse Mercator
15
(No Transcript)
16
(No Transcript)
17
(No Transcript)
18
Spatial Analysis

• Geocoding
• Definition Transforming a location on the
  Earths surface into x and y coordinates so it
  may be represented on a map.
• Common example Geocoding addresses - What are
  the x and y coordinates for our address 288
  North 1460 West?
• Which projection?

19
Spatial Analysis

• Overlays

20
Spatial Analysis

• Themes
• Definition A feature, layer or phenomenon
  represented on a map.
• Examples
• brain cancer
• census tract boundaries
• pollution plume
• city streets
• water systems in London in 1856

21
Spatial Analysis

• Themes (contd)
• Cancer Examples
• cancer screening
• cancer incidence
• cancer cases detected at late stage
• cancer survival
• cancer mortality

22
Spatial Analysis

• Attributes
• Definition Characteristics of the feature being
  mapped.
• Examples
• street starts at point x1, y1 and travels to
  point x2, y2
• color is blue
• name labels
• death rate (for polygon) is 78.2
• contour lines represent 250 vertical feet
  elevation
• contour lines represent logarythmic
  increases/decreases in disease rate

23
Spatial Analysis

• Types of Maps
• Isopleth (points and contours, raster)
• Clusters
• Raster algebra, kriging
• Public health applications

24
Clinton/Sunset TCE Plume With Shifted Cancer
Cases and Ownership Polygons
25
(No Transcript)
26
(No Transcript)
27
(No Transcript)
28
Spatial Analysis

• Isopleth Pros and Cons
• Pros
• You can get more precise view of phenomenon
• Cons
• You need more complex raster algebra to compute
  rates

29
Spatial Analysis

• Types of Maps
• Chloropleth (polygons, vector-based)
• Common ploygons (county, LHD, census tract, ZIP
  code)
• Boundaries, Centroids
• Public health applications

30
Spatial Analysis

• A polygon is a many-sided geometric shape. GIS
  software records it as a series of nodes and
  vectors. Together the nodes and vectors are
  called a shape file.

31
(No Transcript)
32
(No Transcript)
33
(No Transcript)
34
Percentage of Births That Were Born to Adolescent
Mothers by Whether the Rate Was Higher, Lower, or
Not Different (Statistically) from the State
Rate. Utah, 1994-96.
Percentage for a small areas was considered
different from the state rate if its 95
confidence interval did not include the state
rate. Small area designation was based on
residence of mother. Data Source Utah Department
of Health, Bureau of Vital Records.
35
Spatial Analysis

• Chloropleth Pros and Cons
• Pros
• Computation of rates is simple (providing you
  have population denominators for areas)
• Cons
• Not as precise a view
• The smaller the area, the more spatial
  information, but were limited by sparse data and
  lack of population data that matches numerator
  data.
• A cluster could lap two areas or appear in a
  populated area and be washed out by the large
  population.

36
A Geographic Information Analysis ofUrban Infant
Mortality Rates

• Gerard Rushton 1 , Diane Krishnamurti 2 , Rajesh
  Krishnamurthy 1 and Hu Song 3
• 1. Department of Geography, The University of
  Iowa, Iowa City, Iowa 52242
• 2. Iowa Birth Defects Registry, The University of
  Iowa, Iowa City, Iowa 52242
• 3. Iowa Department of Public Health, Des Moines,
  Iowa 52319
• http//www.uiowa.edu/geog/health/

37
Spatial Pattern of Infant Deaths
38
Infant Births in Same Area
39
Raster Grid, or Lattice
40
Geo Areas Correspond to Grid
41
Contour Lines for Infant Death Rates Census
Track Overlay
42
Infant Mortality Rates by Census Tract
43
New York City Maps

• I was just in NYC, and saw these maps. I think
  Ill copy some ideas for IBIS...

44
(No Transcript)
45
(No Transcript)
46
(No Transcript)
47
(No Transcript)
48
On Your Mark, Get Set...

• Software
• ArcView 8.2
• Runs on Windows NT, 2000, XP
• 1,500 for a single-user, stand-alone license
  (UDOH has it on the network. You still need a
  license, but Im not sure about the cost.)
• URL for ArcView and other ESRI products
  http//www.esri.com/
• There are other software providers, but ArcView
  is the product weve always used in OPHA.

49
On Your Mark, Get Set...

• Data to Represent Themes
• Geocoded themes of interest (e.g., births,
  residence of persons with a given disease)
• Shape files
• Overlays - Many available through the states
  Automated Geographic Resource Center (AGRC) at
  maps.utah.gov

50
(No Transcript)
51
Considerations

• How many categories? (translates into how many
  color shades)
• Which colors to use? (hot colors like red often
  used to represent areas of concern, dont forget
  red/green color-blindness, will it print or
  photocopy in BW?)
• General legibility (Ive shown various examples,
  some better than others)

52
(No Transcript)
53
Mapping on IBIS-IRV

• Utahs 42 Community Health Indicators
• Mapped as chloropleth maps (as data will allow)
• LHD
• Small Area
• County
• With interactive overlays user can turn on and
  off
• Zoom feature will allow view of entire state, or
  small area

54
Timeline for IBIS Maps

• Map prototype - done

55
IBIS Map Prototype
56
Timeline for IBIS Maps

• Map prototype - done
• Define community health indicators - done

57
Community Health Indicators
58
Timeline for IBIS Maps

• Map prototype - done
• Define community health indicators - done
• Move existing graphics to new SVG system for
  better-looking charts and maps - end of March/beg
  of April

59
Sizing Bitmaps
60
Timeline for IBIS Maps

• Map prototype - done
• Define community health indicators - done
• Move existing graphics to new SVG system for
  better-looking charts and maps - end of March/beg
  of April

• Get data on IBIS for maps - June
• Get SVG map views attached to data and working -
  July

61
Thank You!